We recently purchased our first fish, Rouge a lovely turquoise and red male Betta. He is yet to eat anything and it has been three days since he moved into his Baby Biorb.

I/we think something is wrong, but we would also like to take this opportunity for the more experienced fish owners to stop us making any unnecessary mistakes.

He seems very lethargic, he doesn't really do a great deal of 'swimming', he tends to laze around the top. Every time he ties to swim he just floats back to the top.

Housing
What size is your tank? 4 Gallon
What temperature is your tank? Room Temperature
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? N/A
Is your tank heated? N
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? TetraMin (Recommended by the sales assistant)
How often do you feed your betta fish? Once a day, 7pm to be exact.

Maintenance
How often do you perform a water change? Scheduled for once every two weeks.
What percentage of the water do you change when you perform a water change? 30%
What type of additives do you add to the water when you perform a water change? Stress Coat+ & Stress Zyme+

While it may sound a like a silly question, I would just like to know if it normal that he seems to do so little? He seemed more active when he was in his 'match box' size aquarium at the pet shop.

Apart from this I would like to know what I am doing wrong? Is there something I could be doing to make his adaptation easier?

Also unless you live in an area where your house is staying constently 80+F you need to invest in an adjustable heater and a cheap glass in tank thermometer. He's also likely too cold.

He should be getting a 20-50% weekly change once the tank is cycled. If it's not established he will need to be monitored and changed more often.

Refusing to eat isn't normal. It usually means he's stressed and/or sick. He may just be freezing cold, so I'd look into the ammonia and temperature fix first. Make sure to adjust the temp very slowly. No more than a couple a degrees per hour. I would also try some different food as that's sub-average. I would try to find New Life Spectrum Betta or if that's one available Omega One makes an ok pellet. NLS is usually found at Petco.

It is a good tank and a good home but just needs some vital improvements. Bettas are tropical fish and are very sensitive to low temperatures. Therefore, you need an aquarium heater. They are pretty cheap online but since you need a heater now, you can run down to Petsmart and buy one there. I have 2 Marina 10c 10 watt heaters. They have bigger sizes for larger tanks; you probably want a 25 watt heater. They are around 20 bucks or so.

Also, for that size tank, you should do at least 1 50% water change per week.

Good luck!

Edit: For new bettas, lack of appetite can be normal but not for long. Only a couple of days at the most. The bettas I have had tried to eat but could never swallow it. Just keep persisting and clean all the uneaten food. :)

Bettas kept at room temperature will be lethargic. They are tropical fish and need to be kept at a minimum of 76 degrees. That could be his problem right there. Also for a 4 gallon tank you should be doing at least 2 water changes a week. I have a 5 gallon and have to do 1 a week. If I don't the ammonia builds up and ammonia can be fatal to fish. There's a really helpful sticky under the betta fish care topic about water changes.